1. Field of the Invention
The present invention relates to a fuel tank structure for an automotive vehicle. More specifically, the present invention relates to a fuel tank structure having a fuel collector unit provided within a fuel tank body at its bottom, which ensures an effective introduction of the fuel into a fuel collector body of the collector unit by utilizing a jet flow of oversupplied return fuel fed from the fuel supply system, and further ensures a sufficient maximum fuel capacity of the fuel collector body without enlarging size thereof.
2. Description of the Background Art
In general, a fuel collector unit is provided at a bottom of a fuel tank body for storing enough fuel to ensure smooth and effective suction by a fuel feed pump when the fuel is biased toward one direction within the tank body due to the centrifugal force exerted on the fuel when a vehicle turns at a curve in a road, or due to the gravity when the vehicle travels along a slope in the road.
Such a fuel collector unit is disclosed, for example, in Japanese First Utility Model Publication No. 6157034. In this conventional structure, a fuel collector unit includes a fuel collector body which is welded to a bottom of a tank body. The collector body is of a bottomed box shape having no top cover and includes a fuel collecting chamber and a substantially L-shaped fuel passage for conducting the fuel within the tank body into the fuel collecting chamber. The fuel passage has an inlet adjacent to the bottom of the tank body for introducing the fuel into the fuel passage and an outlet adjacent to the fuel collecting chamber for discharging the fuel into the collecting chamber.
In the fuel collecting chamber, a lower end portion of a fuel feed tube of a fuel feed pump is disposed directly or through a strainer. Normally, a fuel return tube is also arranged in the fuel collecting chamber for returning oversupplied fuel from the fuel supply system, as, for example, disclosed in Japanese First Utility Model Publication No. 61-59432.
In case the fuel is biased toward one direction due to, for example, the centrifugal force or the gravity as mentioned above with the fuel within the tank bady being relatively small in amount, a maximum fuel capacity of the fuel collector body is generally determined by a vertical position of the inlet of the fuel passage or a vertical position of the outlet of the fuel passage. Specifically, when the vertical position of the inlet or outlet is lower, the maximum fuel capacity becomes smaller, and vice versa. Accordingly, assuming that the vertical position of the inlet or outlet is set higher relative to the tank body bottom, a larger maximum fuel capacity of the collector body is attained so as to ensure the smooth and effective suction of the fuel feed pump when the fuel is biased toward one direction within the tank body.
However, assuming that a fuel level in the tank body becomes below the inlet or outlet of the fuel passage, the fuel cannot be introduced into the fuel passage toward the fuel collecting chamber. Accordingly, when the vertical position of the inlet or outlet of the fuel passage is set higher, an amount of the fuel remaining in the fuel tank becomes larger so that the fuel which is particularly precious and valuable when the remaining fuel is small in amount, can not be used for the vehicle operation, but remained as being non-used. Naturally, this disadvantage should be eliminated.
On the other hand, if a size of the fuel collector body is enlarged, the larger maximum capacity of the fuel collector body is obtained. However, since the fuel collector unit is inserted through a work window provided at an upper wall of the tank body, the size of the fuel collector unit is limited by this requirement. Though it is possible to blow mould the tank body with the fuel collector body therein in case of the tank body being made of synthetic resin, the moulding of this type is very complicated and the insertion of the collector unit through the work window as mentioned above is normally required.